Data collection form– RCTs and NRS

This form can be used as a guide for developing your own data extraction form for interventions reviews of randomised controlled trials (RCTs) and non-randomised studies (NRS). Sections can be expanded and added, and irrelevant sections can be removed. It is difficult to design a single form that meets the needs of all reviews, so it is important to consider carefully the information you need to collect, and design your form accordingly. Information included on this form should be comprehensive, and may be used in the text of your review, ‘Characteristics of included studies’ table, risk of bias assessment, and statistical analysis.

Using this form, or an adaptation of it, will help you to meet MECIR standards for collecting and reporting information about studies for your review, and analysing their results (see MECIR standards C43 to C55; R41 to R45).

Notes on using data extraction form:

  • Be consistent in the order and style you use to describe the information for each report.
  • Record any missing information as unclear or not described, to make it clear that the information was not found in the study report(s), not that you forgot to extract it.
  • Include any instructions and decision rules on the data collection form, or in an accompanying document. It is important to practice using the form and give training to any other authors using the form.
  • If you intend to use GIV analysis in your review, you will need to send us the data extraction forms and full details of how you did the data transformations so our group’s statistician can check your working. Please see our guide to GIV on our website (

Review title or ID
Study ID (surname of first author and year first full report of study was published e.g. Smith 2001)
Report ID
Report ID of other reports of this study including errata or retractions
Notes

General Information

Date form completed(dd/mm/yyyy)
Name/ID of person extracting data
Reference citation
Study author contact details
Publication type (e.g. full report, abstract, letter)
Notes:

Study eligibility

Study Characteristics / Eligibility criteria
(Insert inclusion criteria for each characteristic as defined in the Protocol) / Eligibility criteria met? / Location in text or source (pg & ¶/fig/table/other)
Yes / No / Unclear
Type of study / Randomised Controlled Trial
Quasi-randomised Controlled Trial
Controlled Before and After Study
Contemporaneous data collection
Comparable control sites
At least 2 x intervention and 2 x control clusters
Interrupted Time Series
At least 3 time points before and
3 after the intervention
Clearly defined intervention point
Other design (specify):
Participants
Types of intervention
Types of comparison
Types of outcome measures
INCLUDE / EXCLUDE
Reason for exclusion
Notes:

DO NOT PROCEED IF STUDY EXCLUDED FROM REVIEW

Characteristics of included studies

Methods

Descriptions as stated in report/paper / Location in text or source (pg & ¶/fig/table/other)
Aim of study(e.g. efficacy, equivalence, pragmatic)
Design(e.g. parallel, crossover, non-RCT)
Unit of allocation(by individuals, cluster/ groups or body parts)
Start date
End date
Duration of participation(from recruitment to last follow-up)
Ethical approval needed/ obtained for study / YesNoUnclear
Notes:

Participants

Description
Include comparative information for each intervention or comparison group if available / Location in text or source (pg & ¶/fig/table/other)
Population description(from which study participants are drawn)
Setting(including location and social context)
Inclusion criteria
Exclusion criteria
Method of recruitment of participants(e.g. phone, mail, clinic patients)
Informed consent obtained / YesNoUnclear
Total no. randomised (or total pop. at start of study for NRCTs)
Clusters(if applicable, no., type, no. people per cluster)
Baseline imbalances
Withdrawals and exclusions(if not provided below by outcome)
Age
Sex
Race/Ethnicity
Severity of illness
Co-morbidities
Other relevant sociodemographics
Subgroups measure
Subgroups reported
Notes:

Intervention groups

Copy and paste table for each intervention and comparison group

Intervention Group 1

Description as stated in report/paper / Location in text or source (pg & ¶/fig/table/other)
Group name
No. randomised to group(specify whether no. people or clusters)
Theoretical basis (include key references)
Description (include sufficient detail for replication, e.g. content, dose, components)
Duration of treatment period
Timing (e.g. frequency, duration of each episode)
Delivery (e.g. mechanism, medium, intensity, fidelity)
Providers(e.g. no., profession, training, ethnicity etc. if relevant)
Co-interventions
Economic information
(i.e. intervention cost, changes in other costs as result of intervention)
Resource requirements(e.g. staff numbers, cold chain, equipment)
Integrity of delivery
Compliance
Notes:

Outcomes

Copy and paste table for each outcome.

Outcome 1

Description as stated in report/paper / Location in text or source (pg & ¶/fig/table/other)
Outcome name
Time points measured(specify whether from start or end of intervention)
Time points reported
Outcome definition (with diagnostic criteria if relevant)
Person measuring/reporting
Unit of measurement (if relevant)
Scales: upper and lower limits (indicate whether high or low score is good)
Is outcome/tool validated? / YesNoUnclear
Imputation of missing data(e.g. assumptions made for ITT analysis)
Assumed risk estimate(e.g. baseline or population risk noted in Background)
Power(e.g. power & sample size calculation, level of power achieved)
Notes:

Other

Study funding sources(including role of funders)
Possible conflicts of interest(for study authors)
Notes:

Risk of Bias assessment

(See Chapter 8 of the Cochrane Handbook. Additional domains may be added for non-randomised studies.)

Domain / Risk of bias / Support for judgement
(include direct quotes where available with explanatory comments) / Location in text or source (pg & ¶/fig/table/other)
Low / High / Unclear
Random sequence generation (selection bias)
Allocation concealment(selection bias)
Blinding of participants and personnel(performance bias) / Outcome group: All/
(if separate judgement by outcome(s) required) / Outcome group:
Blinding of outcome assessment(detection bias) / Outcome group: All/
(if separate judgement by outcome(s) required) / Outcome group:
Incomplete outcome data(attrition bias) / Outcome group: All/
(if separate judgement by outcome(s) required) / Outcome group:
Selective outcome reporting?(reporting bias)
Other bias
Notes:

Data and analysis

Copy and paste the appropriate table for each outcome, including additional tables for each time point and subgroup as required.

For RCT/CCT

Dichotomous outcome

Description as stated in report/paper / Location in text or source (pg & ¶/fig/table/other)
Comparison
Outcome
Subgroup
Timepoint(specify from start or end of intervention)
Results / Intervention / Comparison
No. with event / Total in group / No. with event / Total in group
Any other results reported (e.g. odds ratio, risk difference, CI or P value)
No. missing participants
Reasons missing
No. participants moved from other group
Reasons moved
Unit of analysis (by individuals, cluster/groups or body parts)
Statistical methods used and appropriateness of these (e.g. adjustment for correlation)
Reanalysis required? (specify, e.g. correlation adjustment) / YesNoUnclear
Reanalysis possible? / YesNoUnclear
Reanalysed results
Notes:

For RCT/CCT

Continuous outcome

Description as stated in report/paper / Location in text or source (pg & ¶/fig/table/other)
Comparison
Outcome
Subgroup
Time point(specify from start or end of intervention)
Post-intervention or change from baseline?
Results / Intervention / Comparison
Mean / SD (or other variance, specify) / No. participants / Mean / SD (or other variance, specify) / No. participants
Any other results reported (e.g. mean difference, CI, P value)
No. missing participants
Reasons missing
No. participants moved from other group
Reasons moved
Unit of analysis(individuals, cluster/groups or body parts)
Statistical methods used and appropriateness of these (e.g. adjustment for correlation)
Reanalysis required? (specify) / YesNoUnclear
Reanalysis possible? / YesNoUnclear
Reanalysed results
Notes:

For RCT/CCT

Other outcome

Description as stated in report/paper / Location in text or source (pg & ¶/fig/table/other)
Comparison
Outcome
Subgroup
Time point(specify from start or end of intervention)
No. participant / Intervention / Control
Results / Intervention result / SE (or other variance) / Control result / SE (or other variance)
Overall results / SE (or other variance)
Any other results reported
No. missing participants
Reasons missing
No. participants moved from other group
Reasons moved
Unit of analysis (by individuals, cluster/groups or body parts)
Statistical methods used and appropriateness of these
Reanalysis required? (specify) / YesNoUnclear
Reanalysis possible? / YesNoUnclear
Reanalysed results
Notes:

For Controlled Before-and-After study (CBA)

Description as stated in report/paper / Location in text or source (pg & ¶/fig/table/other)
Comparison
Outcome
Subgroup
Time point(specify from start or end of intervention)
Post-intervention or change from baseline?
No. participants / Intervention / Control
Results / Intervention result / SE(or other variance, specify) / Control result / SE(or other variance, specify)
Overall results / SE (or other variance, specify)
Any other results reported
No. missing participants
Reasons missing
No. participants moved from other group
Reasons moved
Unit of analysis (individuals, cluster/ groups or body parts)
Statistical methods used and appropriateness of these
Reanalysis required? (specify) / YesNoUnclear
Reanalysis possible? / YesNoUnclear
Reanalysed results
Notes:

For Interrupted Time Series study (ITS)

Description as stated in report/paper / Location in text or source (pg & ¶/fig/table/other)
Comparison
Outcome
Subgroup
Length of time points measured(e.g. days, months)
Total period measured
No. participants measured
No. missing participants
Reasons missing
Pre-intervention / Post-intervention
No. time points measured
Mean value(with variance measure)
Any other results reported
Unit of analysis (individuals or cluster/ groups)
Statistical methods used and appropriateness of these
Reanalysis required? (specify) / YesNoUnclear
Reanalysis possible? / YesNoUnclear
Individual time point results
Read from figure? / YesNo
Reanalysed results / Change in level / SE / Change in slope / SE
Notes:

Other information

Description as stated in report/paper / Location in text or source (pg & ¶/fig/table/other)
Key conclusions of study authors
References to other relevant studies
Correspondence required for further study information(from whom, what and when)
Notes:

Definitions

Assumed risk estimate / An estimate of the risk of an event or average score without the intervention, used in Cochrane 'Summary of findings tables'. If a study provides useful estimates of the risk or average score of different subgroups of the population, or an estimate based on a representative observational study, you may wish to collect this information.
Bias / A systematic error or deviation in results or inferences from the truth. In studies of the effects of health care, the main types of bias arise from systematic differences in the groups that are compared (selection bias), the care that is provided, exposure to other factors apart from the intervention of interest (performance bias), withdrawals or exclusions of people entered into a study (attrition bias) or how outcomes are assessed (detection bias). Reviews of studies may also be particularly affected by reporting bias, where a biased subset of all the relevant data is available.
Change from baseline / A measure for a continuous outcome calculated as the difference between the baseline score and the post-intervention score.
Clusters / A group of participants who have been allocated to the same intervention arm together, as in a cluster-randomised trial, e.g. a whole family, town, school or patients in a clinic may be allocated to the same intervention rather than separately allocating each individual to different arms.
Co-morbidities / The presence of one or more diseases or conditions other than those of primary interest. In a study looking at treatment for one disease or condition, some of the individuals may have other diseases or conditions that could affect their outcomes.
Compliance / Participant behaviour that abides by the recommendations of a doctor, other health care provider or study investigator (also called adherence or concordance).
Contemporaneous data collection / When data are collected at the same point(s) in time or covering the same time period for each intervention arm in a study (that is, historical data are not used as a comparison).
Controlled Before and After Study (CBA) / A non-randomised study design where a control population of similar characteristics and performance as the intervention group is identified. Data are collected before and after the intervention in both the control and intervention groups
Exclusions / Participants who were excluded from the study or the analysis by the investigators.
Imputation / Assuming a value for a measure where the true value is not available (e.g. assuming last observation carried forward for missing participants).
Integrity of delivery / The degree to which the specified procedures or components of an intervention are delivered as originally planned.
Interrupted Time Series (ITS) / A research design that collects observations at multiple time points before and after an intervention (interruption). The design attempts to detect whether the intervention has had an effect significantly greater than the underlying trend.
Post-intervention / The value of an outcome measured at some time point following the beginning of the intervention (may be during or after the intervention period).
Power / In clinical trials, power is the probability that a trial will obtain a statistically significant result when the true intervention effect is a specified size. For a given size of effect, studies with more participants have greater power. Note that power should not be considered in the risk of bias assessment.
Providers / The person or people responsible for delivering an intervention and related care, who may or may not require specific qualifications (e.g. doctors, physiotherapists) or training.
Quasi-randomised controlled trial / A study in which the method of allocating people to intervention arms was not random, but was intended to produce similar groups when used to allocate participants. Quasi-random methods include: allocation by the person's date of birth, by the day of the week or month of the year, by a person's medical record number, or just allocating every alternate person.
Reanalysis / Additional analysis of a study's results by a review author (e.g. to introduce adjustment for correlation that was not done by the study authors).
Report ID / A unique ID code given to a publication or other report of a study by the review author (e.g. first author's name and year of publication). If a study has more than one report (e.g. multiple publications or additional unpublished data) a separate Report ID can be allocated to each to help review authors keep track of the source of extracted data.
Sociodemographics / Social and demographic information about a study or its participants, including economic and cultural information, location, age, gender, ethnicity, etc.
Study ID / A unique ID code given to an included or excluded study by the review author (e.g. first author's name and year of publication from the main report of the study). Although a study may have multiple reports or references, it should have one single Study ID to help review authors keep track of all the different sources of information for a study.
Theoretical basis / The use of a particular theory (such as theories of human behaviour change) to design the components and implementation of an intervention
Unit of allocation / The unit allocated to an intervention arm. In most studies individual participants will be allocated, but in others it may be individual body parts (e.g. different teeth or joints may be allocated separately) or clusters of multiple people.
Unit of analysis / The unit used to calculate N in an analysis, and for which the result is reported. This may be the number of individual people, or the number of body parts or clusters of people in the study.
Unit of measurement / The unit in which an outcome is measured, e.g. height may be measured in cm or inches; depression may be measured using points on a particular scale.
Validation / A process to test and establish that a particular measurement tool or scale is a good measure of that outcome.
Withdrawals / Participants who voluntarily withdrew from participation in a study before the completion of outcome measurement.

Sources:

Cochrane Collaboration Glossary, 2010. Available from

Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. Available from

Last JM (editor), A Dictionary of Epidemiology, 4th Ed. New York: OxfordUniversity Press, 2001.

Schünemann H, Brożek J, Oxman A, editors. GRADE handbook for grading quality of evidence and strength of recommendation. Version 3.2 [updated March 2009]. The GRADE Working Group, 2009. Available from

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